For grown-ups, the scariest thing about Halloween is the cost of renting costumes (not to mention the dry-cleaning fee).

TDF members need not share this anxiety. For the third year in a row, the TDF Costume Collection will open its doors to TDF members and allow them almost entirely free rein of the Collection, offering rentals at the Collection's lowest price ($45 per costume) and even a discounted dry-cleaning fee of $3.50 per pound.

Best of all: This year the TDF Costume Collection will run a costume contest, with the winner receiving a free costume rental next Halloween.

The special program, which starts Oct. 22, does more than offer a great deal on costumes or a sweet perk for TDF members. Says Greg Poplyk, director of the Collection, it also has an educational component.

"The people who come in generally have no idea about costumes," Poplyk says. "They have a Macy's mentality: 'Do you have this in Size 6?' "

The Collection, however, doesn't work quite like that: It's full of many unique pieces, designed for particular shows. The uninitiated shoppers, Poplyk says, "learn that they have to think more like a costume designer and get creative. They ending up whipping together the most amazing things-things that aren't relevant to a particular script."

The result, Poplyk says, is that "people end up falling in love with the place, and with some of its mystique: the labels that let them know, this was worn by Clifton Webb, or these were Lynn Thigpen's shoes."

He expects a few recent acquisitions to be very popular this Halloween: "Recently, a two-headed sweater came in, and some Vampira-type clothes were donated."

The process is simple: Between Oct. 22 and Oct. 31, TDF members need to RSVP to let the Collection know when they'll be stopping by (the Collection is located in a Chelsea warehouse, at 22nd ). The Collection is even opening its doors for one Saturday, Oct. 27 from 10 a.m. to 4 p.m. Returns can come in as late as Nov. 3 (the following Saturday) up till 4 p.m.

While in previous years the Collection limited rentals to two per member; this year the Collection will rent as many costumes as a member (and perhaps a few member's friends) can carry out and back.

I'll race you for that two-headed sweater.

For more information about the TDF Costume Collection, call (212) 989-5855 or go here.